A benchtop comparison of drying methods relevant to failed spent nuclear fuel

A drying rig has been constructed to allow detailed comparison of both vacuum drying and flowed gas drying of spent nuclear fuels in response to the upcoming closure of the Thorp reprocessing facility at Sellafield, UK. Drying will be needed ahead of disposal possibly ahead of dry interim storage of stainless steel clad Advanced Gas-cooled Reactor fuel. A large number of tests have been carried out using the same small scale simulated fuel pin. The overall results suggest that the drying rate obtained from vacuum drying is significantly higher than when carrying out flowed gas drying. When energy usage is accounted for the drying efficiency is increased still further. Testing also considered different defects; pinholes and stress corrosion cracks. Despite the theoretical open area of the crack being potentially greater than for a pinhole, the pinholed samples were found to have a considerably higher drying rate.